[PATCH] fix slab allocator for non zero boot cpu

[PATCH] fix slab allocator for non zero boot cpu

[Anton Blanchard]

Hi,

The slab allocator doesnt initialise ->array for all cpus. This means
we fail to boot on a machine with boot cpu != 0. I was testing current
2.5 BK.

Luckily Rusty was at hand to explain the ins and outs of initialisers
to me. Manfred, does this look OK to you?

Anton

===== mm/slab.c 1.46 vs edited =====
--- 1.46/mm/slab.c	Sat Nov  2 08:34:38 2002
+++ edited/mm/slab.c	Tue Nov  5 15:55:55 2002
@@ -437,7 +437,8 @@
 /* internal cache of cache description objs */
 static kmem_cache_t cache_cache = {
 	.lists		= LIST3_INIT(cache_cache.lists),
-	.array		= { [0] = &initarray_cache.cache },
+	/* Allow for boot cpu != 0 */
+	.array		= { [0 ... NR_CPUS-1] = &initarray_cache.cache },
 	.batchcount	= 1,
 	.limit		= BOOT_CPUCACHE_ENTRIES,
 	.objsize	= sizeof(kmem_cache_t),

Re: [PATCH] fix slab allocator for non zero boot cpu

[Manfred Spraul]

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Anton Blanchard wrote:

>Hi,
>
>The slab allocator doesnt initialise ->array for all cpus. This means
>we fail to boot on a machine with boot cpu != 0. I was testing current
>2.5 BK.
>
>Luckily Rusty was at hand to explain the ins and outs of initialisers
>to me. Manfred, does this look OK to you?
>
I don't like the patch - it removes the safety net.

initarray_cache is __initdata, and is replaced with actual data after 
the kmalloc caches work, but only for the cpu that performed the 
bootstrap (end of kmem_cache_sizes_init())

With your patch, the pointer to the head arrays of the other cpus still 
point to an __initdata variable. It's even oopsable, if a 
CPU_ONLINE_PREPARE is failed by another subsystem.

What about the attached patch?

--
    Manfred

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